DIFFERENTIAL-EFFECTS OF CYSTEAMINE ON HEAT-SHOCK PROTEIN INDUCTION AND CYTOPLASMIC GRANULATION IN ASTROCYTES AND GLIOMA-CELLS

The sulfhydryl agent, cysteamine (CSH), promotes the accumulation of a utofluorescent, peroxidase-positive cytoplasmic granules in cultured a stroglia akin to those which naturally accumulate in astrocytes of the aging periventricular brain. Both in vitro and in situ, CSH rapidly i nduces various heat shock proteins (HSP) in astrocytes long before gra nulation occurs. In the present study, we determined that CSH treatmen t resulted in an increase in HSP 27, HSP 90 and heme oxygenase (HO-1) at both the protein and mRNA level. We also showed that C6 glioma cell s, unlike primary astrocytes, constitutively express HSP 27, HSP 90 an d HO-1 at low levels. Moreover, CSH is incapable of eliciting further HSP expression or inducing granulation in the glioma cells. Our result s support the hypothesis that the biogenesis of redox-active astrocyti c inclusions in CSH-treated glial cultures and in the aging periventri cular brain is dependent on an antecedent cellular stress response.